DC-DC converters, as an example of power converters, are often used in electronic devices, electronic systems, and the like. In order to improve safety of such DC-DC converters in high-power use, there are known input-output isolation DC-DC converters each having isolation, i.e. electric isolation, between its input and output. Some types of input-output isolation DC-DC converters are designed to be able to use various measurement signals correlated with their operation safety while maintaining an increase of their circuit sizes. One example of these types of input-output isolation DC-DC converters is disclosed in Japanese Patent Application Publication No. 2006-101680, referred to simply as a known Patent Publication.
The input-output isolation DC-DC converter disclosed in the known Patent Publication includes: an input-side circuit for converting an input voltage sent from a DC voltage source via a switching element into an AC voltage using switching elements; an output-side circuit for rectifying the AC voltage to an output voltage using rectifier elements; and a transformer. The transformer is equipped with a magnetic core as a magnetic component for transferring the AC voltage from the input-side circuit to the output-side circuit while electrically isolating the input-side circuit and the output-side circuit. The input-output isolation DC-DC converter also includes a controller for controlling the switching elements of the input-side circuit based on the output voltage fed back from the output-side circuit. The controller is equipped with an input-state monitor. The input-state monitor monitors a level of the input voltage, outputs a pulse signal with a predetermined duty factor based on the monitored level of the input voltage, and changes the duty factor of the pulse signal when determining that there is an abnormality in the input-side circuit. When the controller recognizes the change of the duty factor of the pulse signal, the controller turns off the switching elements.